Compounds belonging to fatty acid compounds A can be exemplified by: ##STR2##
These AA, EPA and DHA are important substances acting as precursors of a group called respectively prostaglandine (PG), thromboxane and leucotriene. These latter substances are possessed of respectively characteristic strong physiological activities and, PG, for example, has a blood-platelet-agglutination-inhibitory-action and contracting and dilating action against arterial wall, and thus can be expected to be useful in prevention of thrombosis and arteriosclerosis, and can also be expected to exhibit anti-cancer action. However, former substances cannot be produced in the human body and, therefore, must be supplied from outside the body. These substances are contained largely in marine products, especially in sardines or mackerels. Therefore, said unsaturated fatty acid is extracted from these fishes as sardine oil and mackerel oil, and can be used, as they are or in a form of amide, ester such as alkylester (e.g. ethylester) triglyceride and the like, as medicines or health-aid foods.
On the other hand, these fatty acid compounds A have many unsaturated bonds and poor stability, thus being readily deteriorated in a relatively short period of time. Fishes are often frozen or dried as they are or made into processed foods (e.g. dried bonito or fishes dried whole). Sometimes, EPA or DHA or the like is extracted from fish oil as it is or in a form of ester, which is then refined. Even in this sort of processing, the unstability of fatty acid compounds A is a problem. Besides, fishes or components of fish oils, when processed or stored for a long period of time, produce rusting.
Under the circumstances, the present inventor has made an extensive study and found that a compound represented by the general formula (I): ##STR3## (wherein R.sup.1 and R.sup.2 respectively stand for fatty acid residue, and R.sup.3 stands for (H).sub.3 or (CH.sub.3).sub.3) [hereinafter called Compound (I)] has an action or stabilizing fatty acid compounds A, thus completing this invention.